Flavorings and perfumes are complex liquid mixtures generally of liquid components. Flavoring granules are required for different purposes. Flavoring encapsulation via spray-drying is customary, but in this only relatively fine and irregularly structured particles are produced (R. Buttiker, Dissertation ETH Zurich No. 6148).
An alternative to spray-drying is producing flavoring granules via fluidized-bed spray agglomeration. EP A 070 719 describes, for example, the production of flavoring granules in a conventional batch-operated fluidized bed. An emulsion of the flavorings to be granulated is sprayed into a fluidized bed which consists of air-fluidized particles. The particles then act as nuclei for the formation of the granule grains.
WO 97/16078 describes the production of flavoring granules in a conventional batch-operated fluidized-bed rotor granulator. The rotor granulator generates a vortexing of the fluidized bed present therein by means of a rotating base plate. In this process material can only be sprayed onto previously introduced cores, so that the flavoring content of the final product is very low.
Both processes operate batchwise, that is to say after processing a spray-solution batch, the production process is terminated and the granules are taken out of the apparatus. A new spray solution batch must then be processed. For reasons of economic efficiency, the processes must therefore be operated with high bed contents. For preset granule growth, a corresponding amount of spray solution must be evaporated. Therefore the high bed contents lead to long residence times of the granules which are in the range of hours. However, the long residence time with simultaneous heat stress of the granules in an air steam leads to correspondingly high losses in the volatile flavorings. Reducing air temperature and/or air throughput does not decrease the flavoring loss, since then, inevitably, the time for evaporating the spray solution is extended.
A further disadvantage of the process according to EP A 070 719 is that the products it produces must be rescreened to produce narrow particle size distributions. Firstly this is an additional labor cost, secondly valuable material is lost in the course of this.
A disadvantage in WO 97/16078 is the high proportion of filler in the granule core (approximately 60 to 90% by weight) and the adsorption of the flavorings to the granules which is only at the surface. The surface adsorption reduces the protection of the flavorings, limits the maximum loading and leads to undesirably high contents of flavorings of the surface of the granules.
Although the granules produced according to EP A 070 719 or WO 97/16078 can be provided with a coating in order to adjust the solubility and flavoring-release behavior, or to achieve a specific protective action, the still relatively non-uniform particle size distribution and the relatively irregular granule surface make uniform coating with constant coating thickness difficult. An actually time- or temperature-controlled release of the flavorings or perfumes can thus not be achieved.